SEA-FISHERIES LABORATORY. 



191 



sharks and dogfishes, there is no direct connection between 

 the male and female at the breeding season. 



The generative organs are the parts of the body in 

 which the spawn is formed. 



The Male Fish. — The generative organ is the testis 

 or soft roe; the mitt is formed in this. The milt consists 

 of sperms. 



The Female Fish. — The generative organ is the 

 ovary or hard roe ; the spawn proper is formed in this. 

 The spawn consists of eggs. 



-Shel 



.HecLcl- 



To-ll-fs'iece 



Or 



Fla.4e.l]vm 



The sperm of a fluke 

 magnified 1,500 dia. 



Micro'pyle 



The egg of a fluke magnified 

 30 dia. 



Fertilisatio n. — The way in which the eggs of 

 a fish, such as the flounder or cod, are fertilised will be 

 shewn in the hatchery. If the eggs are simply taken 

 from the female fish, and allowed to remain iu clear sea- 

 water, no development takes place. But if the milt from 

 the male is mixed with the water in which the eggs are 

 floating fertilisation takes place. One sperm enters each 

 ^gg through the micropyle, which then closes. The 

 development of the egg then begins. 



